wip: tool call structure investigation and e2e tests

- Add debug logging for tool call payloads in agent-stream-view
- Add e2e tests to verify tool call structure for Claude and Codex agents
- Include sidebar toggle and horizontal scroll improvements from previous work

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

packages/app/src/components/agent-stream-view.tsx

@@ -283,6 +283,8 @@ export function AgentStreamView({
       case "tool_call": {
         const { payload } = item;
 
+        console.log("[TOOL_CALL_DEBUG]", JSON.stringify(payload, null, 2));
+
         if (payload.source === "agent") {
           const data = payload.data;
           const toolLabel = data.displayName ?? `${data.server}/${data.tool}`;